Read below a guest article by Nico Arbeck, Head of Department Material Use at C.A.R.M.E.N. e.V.
Final report available
Together with nine partners, C.A.R.M.E.N. e.V. carried out the model project “Practical test of compostable bags – circular economy with compostable fruit and vegetable bags” from December 2020 to February 2022. The project was funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy as part of the bioeconomy strategy “Zukunft.Bioökonomie.Bayern”. The strategy includes an action plan with a series of 50 different measures, and the practical test of the compostable bags is the first one that has already been completed.
With this strategy Bavaria is taking its first major step toward a new economic system. It is based on biogenic, renewable resources instead of fossil, finite resources and is oriented toward natural material cycles. The focus is on resource efficiency and sustainability. The aim is to meet global challenges such as climate change, environmental pollution, and dwindling fossil resources as well as to transform Bavaria into a sustainable business and agricultural location fit for the future. Innovative, bio-based and compostable plastic products (= compostable materials) can contribute to this, as they use biogenic raw materials and increase the circular economy and sustainability through the multiple use of a product.
Practice test of the compostable bag
In Germany, more than 3 billion thin fruit and vegetable bags are used in retail outlets every year and they are mostly used only once (UBA 2022). At the same time, the misthrow of conventional plastic bags makes it difficult for composting facilities to process separately collected biowaste. The obtained compost can be of reduced quality containing plastic residues. Furthermore, this can lead to microplastic pollution in agricultural soils if the compost is used on the field. To test the multiple use of bio-based, compostable fruit and vegetable bags in practice, C.A.R.M.E.N. e.V. collaborated with grocery stores, consumers, and waste management bodies in the defined model region Straubing. Here a compostable fruit and vegetable bag was offered in the markets under the term “Bio-Beutel / bio-bag”. They are an innovative bio-based, compostable product based on renewable raw materials. The compostable bag is suitable for the use as transport packaging, keep-fresh bag for food, and as a collection bag for organic kitchen waste. It conserves fossil, finite resources and promotes natural material cycles. The “bio-bag” was provided free of charge at the self-service counters of the four participating EDEKA and REWE retail stores in Straubing.
The labelling of the bag with the Seedling logo was correctly interpreted by most of the respondents. The majority of the surveyed also clearly recognized that the compostable bag can be used for hygienic collection and disposal of biowaste. Even though the compostable bag was predominantly identified as easily distinguishable from conventional plastic bags due to its design and the information printed on it, some participants still wished for even clearer labelling, e.g., through a more conspicuous colour scheme. According to the polls, the majority would be willing to pay a low cent amount, nevertheless many would prefer a free bag.
Excellent compost quality in Straubing – no adverse effects from compostable bags
In order to be able to document the volume of new bags in the biowaste collection during the project period, samples were taken from the biowaste on three different dates. One sample was taken before the test started, one during halftime, and a third at the end of the test phase. Already the first sorting showed that the majority of the Straubing residents is collecting most of its household biowaste in commercially available biowaste bags. The analysis showed that the use of bio-bags has no negative effects on the quality of the compost. The distributed bio-bags, as well as the commercially available biowaste bags, were completely degraded in the given rotting times of the composting plant and no film residues of the compostable bags could be detected in the final compost.
All surveys, conducted during the project, demonstrated a broad consumer acceptance of the new bio-bag. The majority found the compostable bag’s design attractive and was completely satisfied with its features (e.g., stability, feel, shape or size, smell, durability, keeping food fresh, and collecting kitchen biowaste). It also felt well informed about the use of compostable bags and was able to use the compostable bag appropriately due to the clear messages printed on it. The surveys showed that most consumers used the compostable bag for the collection and the disposal of biowaste via the biowaste garbage can. Some respondents even saw their own willingness to collect increased. But only a small proportion of consumers stated that they already used the compostable bag to store fruit and vegetables.
The biowaste analysis revealed a slight increase in the share of conventional plastic bags in the collected biowaste during the analysis period. However, due to the applied investigation methodology and sample size it was not possible to directly link this finding with the implementation of the practical test. The results of the analysis confirmed a basically very high acceptance amongst Straubing’s consumers towards the collection of domestic biowaste in compostable biowaste bags. At the same time, the results showed that the bio-bag was also used for the collection of biowaste disposed in the compost bin. The compost analysis testified a consistently good compost quality. The fragments of the sorted-out foil plastics were analysed to determine the type of plastic. No compostable material foil fragments were detected in any of the compost samples taken during the three analysis campaigns. This is even more remarkable when one considers that most of the foils contained in the biowaste input were compostable material foils.
The test results clearly showed that the bio-bag can improve the high-quality separate collection of biowaste and, at the same time, reduce the risk of microplastic entering agricultural soils.
The project results will help to further advance the awareness of and the demand for innovative compostable bioplastic bags on the consumer side and amongst businesses. They will also help to improve the corresponding legal framework. Publications, technical articles, and lectures by C.A.R.M.E.N. e.V. and the project partners will follow in the coming months to foster these goals and to initiate possible follow-up projects. The model project can, thus, serves to contribute to the implementation of the Bavarian bioeconomy strategy and to the transformation towards a biobased, sustainable economy.
Click here for further information on the project (in German).